1. Field of the Invention
This invention relates to an optical pickup apparatus and disk drive apparatus, and particularly to the technology for preventing a collision between an optical disk and an objective lens and preventing and reducing damage of a signal recording layer of the optical disk.
2. Description of the Related Art
As a mass storage information recording medium, cited are various optical disks such as CD-ROM (Compact Disk Read Only Memory), CD-R (Compact Disk Recordable), CD-RW (Compact Disk Rewritable), DVD-ROM (Digital Versatile Disk Read Only Memory), DVD-RW (Digital Versatile Disk Rewritable) and other optical reading type disks, a magneto-optical disk, a phase change optical disk and the like.
In a disk drive apparatus for performing recording and/or reproducing to the above optical disks, a focus servo is used for focusing beam light on a signal recording layer of the optical disk, and when the focus servo comes off, an objective lens for focusing the beam light on the signal recording layer of the optical disk and the optical disk collide to damage the optical disk or the objective lens, resulting in the fear that they are disabled from recording and reproducing a signal.
Attempts have been made to dispose a buffer member made of a material having cushioning property such as non-woven fabric, felt or the like in a surface of a lens holder holding the objective lens that is opposite to the optical disk heretofore, whereby when the focus servo comes off, the optical disk collides with the buffer member before it collides with the objective lens so that the objective lens can be prevented from colliding with the optical disk and the optical disc can be prevented from being damaged.
The conventional disk drive apparatus, however, has the problem that dust such as waste thread or the like is scrubbed from the buffer member and scattered in the device to cause a trouble.
In recent years, with the development into mass storage and high density optical disk, a work space, that is, the space between the objective lens and the disk surface with the servo motor kept on running has been decreased so as to increase the risk of a collision between the objective lens and the optical disk.
With the development into mass storage and high density, the thickness of a protective layer covering the signal recording layer of the optical disk has been decreased, resulting in the problem that the signal recording layer of the optical disk is liable to be damaged by the collision between the optical disk and the objective lens.
The present invention has been made in view of the above circumstances to prevent a collision between an optical disk and an objective lens and prevent and reduce damage of a signal recording layer of the optical disk.
According to an aspect of the invention, an optical pickup apparatus includes an objective lens for applying a light beam to a signal recording layer of an optical disk, a lens holder for supporting the objective lens, and a coating layer formed on the disk side end face of the lens holder, that is, the end face opposite to the optical disk, and the coating layer is formed of a material softer than the optical disc and having favorable slidability, and projected over the objective lens toward the optical disk.
Thus, in the above optical pickup apparatus of the invention, even if a focus servo comes off so that the optical disk and the objective lens approach, the optical disk comes into contact with the coating layer before it collides with the objective lens so as to prevent a collision between the optical disk and the objective lens.
Though the optical disk comes into contact with the coating layer, the coating layer is formed of the material softer than the optical disk and having favorable slidability so that the optical disk goes with a slight damage.
According to another aspect of the invention, the optical pickup apparatus includes an objective lens for applying a light beam to a signal recording layer of an optical disk, a lens holder for supporting the objective lens, a lens protector provided on the lens holder to surround the periphery of the objective lens, and a coating layer formed on the disk side end face of the lens protector, that is, the end face thereof opposite to the optical disk, and the coating layer is formed of a material softer than the optical disk and having favorable slidability and projected from the objective lens toward the optical disk.
Thus, in the above optical pickup apparatus of the invention, even if a focus servo comes off so that the optical disk and the objective lens approach, the optical disk comes into contact with the coating layer before it collides with the objective lens so as to prevent a collision between the optical disk and the objective lens.
Although the optical disk comes into contact with the coating layer, the coating layer is formed of the material softer than the optical disk and having favorable slidability so that the optical disk goes with a slight damage.
According to still another aspect of the invention, the optical pickup apparatus includes an objective lens for applying a light beam to a signal recording layer, and a lens holder for supporting the objective lens, the disk side end face of the lens holder, that is, the end face positioned in the periphery of the objective lens opposite to the optical disk is disposed closer to the optical disk than the objective lens, an objective lens protective surface is formed for preventing a collision between the objective lens and the optical disk when the lens holder and the optical disk approach, and in the disk side end face of the lens holder, an objective lens protective surface is not formed at least in a portion with a designated width positioned on the upstream side of the objective lens with respect to the rotation of the optical disk.
Thus, in the above optical pickup apparatus of the invention, even if a focus servo comes off so that the optical disk and the objective lens approach, the optical disk comes into contact with the objective lens protective surface before it collides with the objective lens so as to prevent a collision between the optical disk and the objective lens.
The optical disk comes into surface contact with the objective lens protective surface, so that the optical disk goes with a slight damage.
According to an aspect of the invention, the disk drive apparatus includes an optical pickup apparatus adapted to apply a light beam to a signal recording layer of an optical disk rotated by a disk rotating device, thereby reading and/or recording a signal to the signal recording layer, the optical pickup apparatus includes an objective lens for applying a light beam to the signal recording layer, a lens holder for supporting the objective lens, and a coating layer formed on the disk side end face of the lens holder, that is, the end face thereof opposite to the optical disk, and the coating layer is formed of a material softer than the optical disk and having favorable slidability.
Thus, in the above disk drive apparatus of the invention, even if a focus servo comes off so that the optical disk and the objective lens approach, the optical disk comes into contact with the coating layer before it collides with the objective lens so as to prevent a collision between the optical disk and the objective lens.
Although the optical disk comes into contact with the coating layer, the coating layer is formed of the material softer than the optical disk and having favorable slidability so that the optical disk goes with a slight damage.
According to another aspect of the invention, the optical disk drive apparatus includes an optical pickup apparatus adapted to apply a light beam to a signal recording layer of an optical disk rotated by a disk rotating device, thereby reading and/or recording a signal to the signal recording layer, the optical pickup apparatus includes an objective lens for applying a light beam to the signal recording layer, a lens holder for supporting the objective lens, a lens protector provided on the lens holder to surround the periphery of the objective lens, and a coating layer formed on the disk side end face of the lens protector, that is, the end face thereof opposite to the optical disk, and the coating layer is formed of a material softer than the optical disk and having favorable slidability and projected from the objective lens toward the optical disk.
Thus, in the above disk drive apparatus of the invention, even if a focus servo comes off so that the optical disk and the objective lens approach, the optical disk comes into contact with the coating layer before it collides with the objective lens so as to prevent a collision between the optical disk and the objective lens.
Although the optical disk comes into contact with the coating layer, the coating layer is formed of the material softer than the optical disk and having favorable slidability so that the optical disk goes with a slight damage.
According to still another aspect of the invention, the disk drive apparatus includes an optical pickup apparatus adapted to apply a light beam to a signal recording layer of an optical disk rotated by a disk rotating device, thereby reading and/or recording a signal to the signal recording layer, the optical pickup apparatus includes an objective lens for applying a light beam to the signal recording layer, and a lens holder for supporting the objective lens, the disk side end face of the lens holder, that is, the end face positioned in the periphery of the objective lens opposite to the optical disk is disposed closer to the optical disk than the objective lens, an objective lens protective surface is formed for preventing a collision between the objective lens and the optical disk when the lens holder and the optical disk approach, and in the disk side end face of the lens holder, an objective lens protective surface is not formed at least in a portion with a designated width positioned on the upstream side of the objective lens with respect to the rotation of the optical disk.
Thus, in the above disk drive apparatus of the invention, even if a focus servo comes off so that the optical disk and the objective lens approach, the optical disk comes into contact with the objective lens protective surface before it collides with the objective lens so as to prevent a collision between the optical disk and the objective lens.
The optical disk comes into face contact with the objective lens protection surface, so that the optical disk goes with a slight damage.